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Behavioral studies show UV contributes to marsupial color vision
March 21, 2006Work reported this week provides new evidence that marsupials, like primates, have functional color vision based on three different types of color photoreceptor cones-but unlike primates, a component of marsupial color vision includes sensitivity to ultraviolet wavelengths. In the study, researchers employed behavioral tests to show that at least one type of marsupial uses its detection of UV light as part of its ability to discriminate between colors. The new work is reported by a group including Dr. Catherine Arrese of the University of Western Australia and appears in the March 21st issue of Current Biology.
The most prevalent system of color vision in mammals is known as dichromacy, which is a color-detection system based on two types of cone photoreceptors-those sensitive to short (SWS) and medium-to-long (M/LWS) wavelengths. Trichromacy, which is used by humans, was thought to be unique to primates that have re-evolved a third cone type from the duplication of the MWS/LWS gene, which enables the discrimination of green-red colors. But the researchers' previous physiological studies in Australian marsupials provided original evidence for the potential of trichromatic color vision in mammals other than primates. The findings were consistent in several distantly related marsupial species, indicating that the presence of three spectrally distinct cone types, sensitive to short (SWS), medium (MWS), and long (LWS) wavelengths, is a common feature of Australian marsupials. However, since evidence of color vision cannot be derived from physiological studies alone, marsupial trichromacy remained to be established with an unequivocal behavioural approach.
In the new study, the researchers therefore investigated the contribution of the distinct cone types to color vision in the fat-tailed dunnart (Sminthopsis crassicaudata), using additive color mixture experiments in which choice between a colored light (training wavelength) and an additive mixture of two different colored lights (primary wavelengths) is based exclusively on differences in chromatic content. The results revealed that the fat-tailed dunnart possesses functional trichromacy, but that its version of trichromatic vision differs from that of primates in that it includes sensitivity to UV wavelengths. In addition to furthering our knowledge of how mammalian color vision functions, the findings provide an opportunity to re-examine theories on the evolution of this key sensory capacity.
Cell Press
Cell Press
Color Vision Current Events and Color Vision News RSSNew insight into primate eye evolution
Researchers comparing the fetal development of the eye of the owl monkey with that of the capuchin monkey have found that only a minor difference in the timing of cell proliferation can explain the multiple anatomical differences in the two kinds of eyes.
'Gecko vision': Key to the multifocal contact lens of the future?
Nocturnal geckos are among the very few living creatures able to see colors at night, and scientists' discovery of series of distinct concentric zones may lead to insight into better cameras and contact lenses.
Hundreds of natural-selection studies could be wrong, study demonstrates
Scientists at Penn State and the National Institute of Genetics in Japan have demonstrated that several statistical methods commonly used by biologists to detect natural selection at the molecular level tend to produce incorrect results.
Mutated gene in zebrafish sheds light on blindness in humans
Among zebrafish, the eyes have it. Inside them is a mosaic of light-sensitive cells whose structure and functions are nearly identical to those of humans.
Elephant shark genome sequence leads to discovery of color perception in deep-sea fish
The elephant shark, a primitive deep-sea fish that belongs to the oldest living family of jawed vertebrates, can see color much like humans can.
Atomic-resolution views suggest function of enzyme that regulates light-detecting signals in eye
An atomic-resolution view of an enzyme found only in the eye has given researchers at the University of Washington (UW) clues about how this enzyme, essential to vision, is activated.
NYU Researchers id new class of photoreceptors,pointing to new ways sights-and smells-are regulated
The identification of a new class of photoreceptors in the retina of fruit flies sheds light on the regulation of the pigments of the eye that confer color vision, researchers at New York University's Center for Developmental Genetics report in a new study appearing in the Public Library of Science's journal, PloS Biology.
NYU scientists set stage for understanding how color vision is processed
New York University biologists have mapped the medulla circuitry in fruit flies, setting the stage for subsequent research on how color vision is processed.
Scientists find color vision system independent of motion detection
The vision system used to process color is separate from that used to detect motion, according to a new study by researchers at New York University's Center for Developmental Genetics and in the Department of Genetics and Neurobiology at Germany's University of Würzburg.
New study uncovers secrets behind butterfly wing patterns
The genes that make a fruit fly's eyes red also produce red wing patterns in the Heliconius butterfly found in South and Central America, finds a new study by a UC Irvine entomologist.
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